The Pentagon has admitted buying up and destroying 10,000 copies of an insider's account of life in Afghanistan by an army intelligence officer.

It said that the book, Operation Dark Heart by Lt Col Anthony Shaffer, threatened to divulge state secrets.

Lt Col Shaffer, a bronze star recipient, said he had no intention of jeopardising American lives or damaging national security.

"The whole premise smacks of retaliation," he told CNN. "Someone buying 10,000 books to suppress a story in this digital age is ludicrous."

The book was cleared for publication by his superiors at the US army reserve command despite being critical of strategy in Afghanistan.

But shortly before it was due to leave the warehouse, the Pentagon's intelligence unit raised concerns.

The author has said he has fallen victim to an increased sensitivity about inside information following the release by the Wikileaks website of thousands of military documents detailing the conduct of the war, and the resignation of Gen Stanley McChrystal as US commander in Afghanistan because of disparaging comments about the Barack Obama administration made by his aides to a magazine.

Lt Col Shaffer also said that the "Pentagon wanted to shut this off until after the election", because it was "more bad news". Major congressional elections are being held on Nov 2.

In a statement, the Pentagon said it "decided to purchase copies of the first printing because they contained information which could cause damage to national security". The books were destroyed on Sep 20.

The few copies of the book that managed to evade the Pentagon's dragnet are now being exchanged for up to $2,000 on the internet.

Lt Col Shaffer has since agreed to a redacted version of the book, which is released this week. He has said that though the Defence Department promised "surgical" censorship the book has been substantially redacted throughout its 300 pages with black marks replacing words or passages deemed unacceptable.

"When you look at what they took out, it's lunacy," he said.

An early line in the book reads: "Here I was in Afghanistan (redaction). My job: to run the Defence Intelligence Agency's operations out of (redaction) the hub for U.S. operations in country."

It comes as the Watergate journalist, Bob Woodward, publishes his book Obama's Wars, which shines a light on the in-fighting between top officials that threatened to tear the White House apart.